JP5298664B2 - Shape measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shape measuring device which enables attainment of image information different in a focal plane in a short time, without continuous and mechanical driving of a measuring object. <P>SOLUTION: A light quantity sensor 2 includes sensor elements 2a-2d in a one-dimensional direction. The sensor elements 2a-2d are made to form focuses Va, Vb, Vc and Vd at heights Ha, Hb, Hc and Hd near a measuring line 12 of the measuring object 1 by an optical system (not shown). The surface 13 of the measuring object 1 is colored black and white dividedly by coating and the sensor elements 2a-2d and the optical system are moved to scan in the direction from a region Y1 to a region Y8 of the measuring object 1. A light quantity value of each sensor element is read out at the time and recorded together with the position thereof. The light quantity value of each sensor element corresponds to black 13b or white 13w of the surface color when the focus is formed on the surface 13 of the measuring object 1 while having a value of gray made up of black and white mixed together when the focus is not formed thereon. By evaluating formation of the focus as to the heights Ha-Hd from these light quantity values of the black, white and gray, the height as to each region Y is identified. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention is an apparatus for measuring the height and shape of the surface of an object to be measured accurately and at high speed, and in particular, measuring a small area and a small height such as a rib height inspection of a plasma display panel and an electrode inspection of an integrated circuit. The present invention relates to a shape measuring apparatus that performs the above at a higher speed.

  Conventional methods for measuring the height of an object to be measured include a confocal measurement method, a triangulation method, a light cutting method, and a focusing method.

  The confocal measurement method has an optical system with a pinhole at the image side focal position of the objective lens, and the amount of light passing through one pinhole is the largest when the objective lens is in focus. Measure the displacement of the object using.

  This confocal measurement method has the advantage that it is not easily affected by the reflectivity and surface condition of the object to be measured. However, it requires an objective lens or a mechanism to move the object to be measured up and down. Only one point of information on the object to be measured can be obtained, and there is a disadvantage that the time required for measurement is long because it is necessary to scan the measurement point in order to obtain planar height information.

  Further, in the triangulation system, illumination focused on an object is irradiated, and a part of the reflected light is imaged on a sensor by a light receiving lens. When this object is displaced, the angle at which the reflected light is collected changes, and the imaging position on the sensor moves. By capturing this, the displacement of the object is measured. This method has the advantage that high-speed measurement is possible because there is no moving part, but has the disadvantage that the measurement accuracy tends to deteriorate due to the reflectivity, surface condition, inclination, etc. of the object to be measured.

  The light cutting method is a type of triangular distance measuring method, and the illumination to be focused on the object is in the form of a line, and the two-dimensional sensor is used as the light receiving sensor, so that the displacement of the object to be measured is captured in a line. It is.

  The focusing method is a method of measuring the displacement of an object included in an image by evaluating the degree of focusing on a plurality of images with different focal points by an image processing method (see Non-Patent Document 1). . And even when the unevenness of the object to be measured is large, it is possible to measure correctly, and there is an advantage that the height information of a plurality of positions included in the image can be obtained by one measurement. Generally, the objective lens or the object to be measured is moved up and down. A moving mechanism is necessary.

  On the other hand, for example, a device has been proposed in which the focal plane is displaced at high speed by changing the optical optical path length by, for example, sequentially rotating and switching parallel plates inserted in the optical path (see Patent Document 1). ), The change in the optical path length is discontinuous, and the light receiving element becomes a dead zone during the period when the optical element is switched.

In any of the methods, mechanical driving is required to displace the focal plane, and the optical system must be stationary with respect to the object to be measured during the measurement.
Japanese Patent Laid-Open No. 8-304043 Mitsuhiro Ishihara, Hiromi Sasaki, "High-speed 3D shape measurement by focusing method", Journal of Precision Engineering vol.63, No.1, 1997, pp124

  However, such a conventional technique has a drawback that it is difficult to increase the operation speed because it involves a mechanical operation to displace the focal plane. In addition, the conventional technique has a problem that it is difficult to reduce the time required for measurement because the observation position of the optical system needs to be stationary during measurement.

  SUMMARY OF THE INVENTION The present invention solves the above-described problems of the prior art, and an object thereof is to provide an inexpensive shape measuring apparatus that can obtain image information of continuously measuring objects having different focal planes in a short time.

In order to achieve the above object, the shape measuring apparatus according to claim 1 of the present invention forms an image of the surface of an object to be measured having a black region and a white region in a plane having the same height. An optical system for scanning, a plurality of light quantity sensors arranged on focal planes corresponding to different surfaces of the object to be measured, and a drive system for scanning the surface of the object to be measured by the optical system And detecting the focal point by processing the electrical signals respectively corresponding to the black region and the white region obtained from the plurality of light quantity sensors and performing the focus evaluation, and from the focal point, the object to be measured is detected. A signal processing unit for measuring the shape of the surface , wherein the white area is disposed in front of or behind the black area in a direction in which the object to be measured is scanned in a plane having the same height. and said that you are.

  According to the above configuration, it is possible to obtain image information continuously with respect to the object to be measured, and it is possible to obtain image information with different focal planes without mechanical driving, thereby shortening the measurement time. .

  According to the present invention, compared to the conventional method, image information having different focal planes can be obtained continuously without being stationary with respect to the object to be measured, so that the time for shape measurement can be shortened. There is an effect.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
First, the apparatus configuration and operation of the first embodiment will be described.

  FIG. 1 is a block diagram showing the overall configuration of the shape measuring apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a diagram for explaining the operation during measurement. As shown in FIG. 2, the points A11a and B11b on the surface of the object to be measured 1 having different heights are focused on different spaces (points A'21a and B'21b) by the lens 32 of the optical system. A plurality of light quantity sensors 2 (sensor elements 2a and 2b) are arranged in a space near the focal point. In the example shown in FIG. Each sensor element 2a and sensor element 2b is placed at the focal point of each of the points A11a and B11b on the surface of the DUT 1. Also, all the optical systems related to illumination are omitted.

  When the drive system 4 (see FIG. 1) is operated in the direction of the arrow in FIG. 2 to scan the surface of the object 1 to be measured, the sensor element 2a changes only like the waveform Wa1 when the height of the point A11a is Ha. Output electrical signals. Similarly, the sensor element 2b outputs an electrical signal like the waveform Wb1 only when the height of the point B11b is Hb. When each sensor element is not located at a focal point, the output fluctuation is small as in the waveforms Wa2 and Wb2.

  This is because when the light quantity sensor is not in focus, the fluctuation in the output is small because the light quantity that is blurred and averaged enters. The sensor element 2a and the sensor element 2b detect only the height Ha and the height Hb, respectively. And in order to detect more height, by arranging many light quantity sensors, it is possible to know a plurality of heights on the DUT 1 in detail. The output electric signal from the light quantity sensor (each sensor element) is processed by a signal processing unit to identify the height.

  Several methods are used as an image processing method for evaluating the degree of focusing for each region based on information obtained from the light quantity sensor. For example, a maximum-minimum method, an average difference square sum method (dispersion method), an average difference absolute value sum method, a difference absolute value sum method, a difference square sum method, and the like can be given.

  Next, a method for processing the measurement results obtained in the first embodiment will be described.

  Details of an image processing method for evaluating the degree of focusing will be described below. Here, the light amount information of the coordinates (x, y) is i (x, y).

First, the maximum / minimum method _EDRG uses the difference between the maximum value and the minimum value in the region as the focus evaluation value, and is defined as the following equation (Equation 1).

平均差二乗和法Ｅ_ＶＡＲとは領域内の光量の代表的値と、各光量センサーの値との差の二乗和を合焦評価値とする方法である。領域内の光量の代表値として相加平均である、下記式（数２）を用いる。

The average difference square sum method E _VAR is a method in which the sum of squares of the difference between the representative value of the light quantity in the region and the value of each light quantity sensor is used as the focus evaluation value. The following equation (Equation 2), which is an arithmetic mean, is used as a representative value of the amount of light in the region.

また、平均差二乗和を、下記式（数３）として定義する。

The mean square sum of differences is defined as

これは一般に標本分散として知られる値である。また二乗の代わりに絶対値を用いてもよく、これを平均差絶対値和法Ｅ_ＶＲＳと呼び、下記式（数４）と定義する。

This is a value commonly known as sample variance. Moreover, you may use an absolute value instead of a square, and this is called the average difference absolute value sum method _EVRS, and is defined by the following formula _| equation (Formula 4).

また代表値として、相加平均のほかにさまざまな要約統計量を用いることができ、例えば相乗平均である、下記式（数５）を用いてもよい。

In addition to the arithmetic mean, various summary statistics can be used as the representative value. For example, the following formula (Equation 5) which is a geometric mean may be used.

このほか、中央値や最頻値などを用いてもよい。

In addition, a median value or a mode value may be used.

The difference absolute value summation method _ESAD is defined as the sum of absolute values of differences from light quantity values at different positions in space. A square may be used instead of the absolute value (difference square summation method), and the evaluation value in this case is called E _SSD . In both cases, the positional relationship in space with the partner whose difference is to be calculated is defined as dx and dy as follows:

ｄｘおよびｄｙの値は被測定物の表面状態や光学分解能によって選択する。

The values of dx and dy are selected according to the surface state of the object to be measured and the optical resolution.

  The evaluation values obtained by the calculation methods listed here all indicate that the greater the numerical value, the greater the degree of focusing.Of course, depending on the calculation method, the larger the degree of focusing, the smaller the numerical value. Is also possible.

  Based on the nine output values obtained from this light quantity sensor, two specific methods using the maximum / minimum method, the average difference sum of squares method (dispersion method), the average difference absolute value sum method, the difference absolute value sum method, and the difference square sum method are used. An example is shown in FIG.

  In the following description, for the sake of convenience, unless there is a special note in the text, the evaluation method is assumed to have a greater degree of focus as the evaluation value is larger. Here, since the focus evaluation is performed based on a plurality of pieces of information obtained from the light quantity sensor, the focus evaluation value has a lower spatial density of information than the obtained light quantity value. If the focus evaluation method and parameters are the same, in order to obtain a more accurate focus evaluation value, more light quantity values obtained from the light quantity sensor may be used. Density decreases. In order to prevent a reduction in the spatial density of the focus evaluation value, it is necessary to select a focus evaluation method capable of performing accurate focus evaluation using a smaller number of light quantity values.

  In FIG. 4, an electrical signal more suitable for signal processing can be obtained from the light quantity sensor 2 by further increasing the numerical aperture of the optical system (lens 32). In general, the in-focus range D of the optical system has a relationship represented by the following formula (Expression 7), where NA is the numerical aperture of the optical system.

そのため、開口数を高めることにより光学系（レンズ３２）の合焦する範囲がより狭くなる。これにより、より小さい焦点面の変位によって、より大きな電気信号の変化が得られるようになる。

Therefore, by increasing the numerical aperture, the focusing range of the optical system (lens 32) becomes narrower. This allows a greater change in electrical signal due to smaller focal plane displacement.

  Further, if the magnification of the optical system (lens 32) and the method of illuminating the device under test 1 are appropriately selected according to the surface state of the device under test 1, an electrical signal more suitable for signal processing may be obtained. is there. For example, there is a method of irradiating illumination from an oblique direction.

  Table 1 shows the result of comparing the various focus evaluation methods shown in the first embodiment using the light amount value actually obtained from the object to be measured.

（表１）より、差分絶対値総和法において、ｄｘ，ｄｙのパラメータを「１」とした場合に最も評価値の変化割合が大きくなっていることがわかる。例えば、表面粗さが３μｍ程度の表面を持つ被測定物の表面２０μｍ四方を、開口数０．４６で空間分解能が１μｍ程度となるような倍率を持つ対物レンズを用いて、１μｍおきに撮像する。

From Table 1, it can be seen that, in the difference absolute value summation method, when the dx and dy parameters are set to “1”, the change rate of the evaluation value is the largest. For example, a 20 μm square surface of an object having a surface with a surface roughness of about 3 μm is imaged every 1 μm using an objective lens having a magnification such that the numerical aperture is 0.46 and the spatial resolution is about 1 μm. .

  The output electric signal obtained from the light amount sensor is 20 points × 20 points in total, which is 400 points. Focus evaluation by using the difference absolute value summation method as an evaluation function for the light amount value obtained by sampling this. As a result of calculating the value, the evaluation value showed a change of about 5% when displaced by 1 μm from the in-focus position. Since the fluctuation of the evaluation value when there was no displacement was about 3% at 3σ, a displacement of 1 μm could be sufficiently detected.

  Here, for example, a light amount sensor having a plurality of sensor elements arranged in a one-dimensional direction is used. The sensor elements are arranged so as to be inclined so that each sensor element is focused at a different height. The inclination of the sensor element is determined according to the height of the object to be measured. For example, when the object to be measured has an unevenness of 100 μm, the inclination of the focal plane must be larger than 100 μm.

  FIG. 5 is a diagram showing a state in which sensor elements are arranged in a one-dimensional direction. By the optical system (lens 32), the sensor elements 2a to 2f of the light quantity sensor 2 are focused on the height Ha to the height Hf at the position Pa to the position Pf of the object 1 to be measured, respectively. Such an arrangement makes it possible to construct a device simply and inexpensively because a commonly used semiconductor one-dimensional image sensor such as a CCD or MOS can be used.

  The operation when a plurality of sensor elements are arranged in the one-dimensional direction will be described below. As shown in the perspective view of FIG. 6A, an apparatus including four sensor elements 2a to 2d in the one-dimensional direction as the light quantity sensor 2 is taken as an example. The sensor elements 2a to 2d of the light quantity sensor 2 are focused on heights Ha, Hb, Hc, and Hd near the measurement line 12 of the object to be measured 1 by an optical system (not shown because it is complicated). , Vd.

  In addition, the surface 13 of the device under test 1 is actually painted black and white as shown in FIG. 6C, but the surface color of the device under test 1 in FIG. Not drawn. Here, the sensor elements 2a, 2b, 2c, 2d and the optical system are moved and scanned in the direction of the arrow in FIG. 6B from the area Y1 of the DUT 1 to the area Y8 in FIG. 6A. As the time advances, the light amount value is read from each sensor element, and the value is recorded together with the position.

  The light quantity value obtained from each sensor element has a value corresponding to black 13b or white 13w depending on the color of the surface if the surface 13 of the DUT 1 is in focus. If the surface 13 of the DUT 1 is not focused, each sensor element has a value corresponding to gray in which black and white are mixed. The light amount values recorded by the light amount sensor are shown in FIGS.

  As shown in FIG. 7A, the time when the sensor element 2d first approaches the area Y1 is T1, and the time when the sensor element 2a scans the area Y8 is T14. The time between them is set to T2 to T13 in order. The time intervals are not necessarily equal. Black, white, and gray indicate light intensity values obtained from the sensor elements. The hatched portion indicates that the sensor element is in a positional relationship where it does not hit the object to be measured, and this portion is irrelevant to the processing.

  FIG. 6 (a) depicts the positional relationship at time T7 in FIG. 7 (a). The sensor elements 2a to 2d correspond to the respective heights Ha to Hd. Further, the position and time are associated with each sensor element based on the time when each sensor element passes through the regions Y1 to Y8. The result is shown in FIG. FIG. 7C shows the result of focusing evaluation performed on the information strings of the heights Ha to Hd.

  In FIG. 7C, the portion shown in black indicates that it is not in focus, and the portion shown in white indicates that it is in focus. Thus, the height of each region Y can be identified. For example, it can be seen that the height Ha is most focused in the vicinity of the region Y1. Thus, the shape along the measurement line 12 of the surface 13 of the DUT 1 can be reproduced.

  Here, the method of moving the light quantity sensor 2 while fixing the object to be measured 1 has been described. However, the light quantity sensor 2 may be fixed by moving the object to be measured 1, or the light quantity sensor 2 and the object to be measured 1 may be fixed. Both may be moved. In addition, here, the process of explanation is divided into several steps for convenience, but it is not always necessary to divide the process in this way.

  The magnification of this optical system is determined by the size of the measurement visual field in the short side direction. The measurement accuracy in this method is determined not by the magnification but mainly by the numerical aperture of the optical system. In order to perform in-focus evaluation, the unevenness present on the surface 13 of the object to be measured 1 needs to be captured as a change in the amount of light. Determine the magnification. For example, when the surface 13 of the DUT 1 has a roughness of about 1 μm, in order to capture this, the magnification is selected so that a higher resolution can be obtained. The information density in the scanning direction is determined by the frequency of reading data from the light quantity sensor and the scanning speed, but this may be determined according to the structure of the surface 13 of the object 1 to be measured, and the resolution in the short side direction of the field of view is not necessarily required. There is no need to match.

  The measurement range in the height direction is determined by the length and pitch of the light quantity sensor 2 in the one-dimensional direction and the degree of inclination of the focal plane. In order to increase the measurement range, the number of sensor elements may be increased, the light receiving elements on the light quantity sensor 2 in the one-dimensional direction may be arranged more roughly, or the degree of inclination of the focal plane may be increased. The measurement resolution in the height direction is obtained by dividing the measurement range in the height direction by the number of sensor elements. Therefore, in order to increase the resolution, the degree of inclination of the focal plane is reduced, or the light quantity sensor in the one-dimensional direction. The intervals between the light receiving elements on 2 may be non-uniform, and the light receiving elements may be arranged more densely in places where the resolution is improved.

(Embodiment 2)
In the second embodiment of the present invention, the light quantity sensor 2 used in the first embodiment is replaced with a two-dimensional sensor, and the height of the object to be measured 1 can be measured by one scan. Is. For example, as shown in FIGS. 8A and 8B, a two-dimensional light quantity sensor 2s configured with 4 × 8 elements (sensor elements 2as1 to 8, 2bs1 to 8, 2cs1 to 8, 2ds1 to 8) is used. The example which scanned the to-be-measured object 1 is shown. Also, the optical system is not drawn in FIG.

  Similar to the description in the first embodiment, the surface of the DUT 1 has a black and white pattern as the pattern 14 as shown in FIG. In order to prevent complication, this pattern is not drawn in FIG.

  In FIG. 8A, the two-dimensional light quantity sensor 2s has a first direction composed of four elements (row sensor elements 2a, 2b, 2c, 2d) and a second direction composed of eight elements (column sensor elements s1 to s8). To do. The two-dimensional light quantity sensor 2s is scanned and measured in a direction orthogonal to the second direction. The directions parallel to the direction of scanning the surface of the DUT 1 are defined as regions Y1 to Y8, respectively. The row sensor elements 2a to 2d scan different heights Ha to Hd, and the column sensor elements s1 to s9 scan different areas X1 to X8, respectively. This is essentially the same as the eight-dimensional one-dimensional light quantity sensor 2 in the first embodiment (that is, s1 (2a, 2b, 2c, 2d) to s8 (2a, 2b, 2c, 2d)). .

  FIG. 9 shows a time series of electrical signals obtained from each sensor element. In FIG. 9, the meanings of black, white, gray, and diagonal lines are the same as those in the first embodiment. Black and white indicate that the optical system is focused on the surface pattern 14 of the DUT 1 and the color of the surface of the DUT 1 at that position is black and white, respectively. Gray indicates that the optical system is not focused on the surface of the DUT 1. The oblique lines indicate that the optical system does not capture the object 1 to be measured.

  At time T1 in FIG. 9, the sensor elements 2ds1 to 8 reach the region Y1. Similarly, at time T7, the sensor elements 2as1 to 8 reach the region Y1. FIG. 8A depicts the positional relationship at time T7. The column sensor elements s1 to s8 correspond to the regions X1 to X8 of the DUT 1. Since the relationship between the time T and the region Y in the scanning direction is known, the time T corresponds to the region Y using this.

  Thereby, information can be rearranged as shown in FIG. Furthermore, if the information on the heights Ha to Hd is arranged, two-dimensional light quantity information on the area XY can be obtained for each height H as shown in FIG. FIG. 12 shows the result of calculating the focus evaluation for each area for this information. Thereby, the height for each region is identified, and the shape of the DUT 1 is obtained. The obtained shape information is shown in FIG.

(Embodiment 3)
As described in the first embodiment, a large number of height levels can be detected by increasing the number of sensor elements of the light quantity sensor 2 (that is, by densely arranging the light quantity sensors 2 at a specific focal position). (The height resolution can be increased). Therefore, Embodiment 3 of the present invention shows an example in which the sensor element 2f of the light quantity sensor 2 in FIG. 5 is divided into three (2f-1, 2f-2, 2f-3) as shown in FIG. ing. In this example, three levels can be detected around the height Hf with a resolution obtained by dividing the height He and the height Hf into three (Hf1, Hf2, Hf3).

  Further, as an application of the third embodiment, when a higher height resolution is required at a specific height of the DUT 1, a sensor element arrangement of the light quantity sensor 2 as shown in FIG. That is, the position difference between adjacent sensor elements in the vicinity of a specific focal position is reduced. The sensor elements are densely arranged at a specific focal position.

  In the case shown in FIG. 15, the height resolution of the sensor elements 2a to 2c and sensor elements 2g to 2i of the light quantity sensor 2 is higher than that of the sensor elements 2d to 2f. Here, the upper limit of the resolution is mainly determined by the evaluation method of the depth of field of the optical system (lens 32) and the information amount of the light amount value that can be used for focusing evaluation. The lower the depth of field, the higher the resolution. The depth of field varies depending on the numerical aperture of the optical system, and the larger the numerical aperture, the shallower the depth of field.

  For example, using a light receiving optical system having a numerical aperture of 0.46, setting the spatial resolution to about 1 μm, and scanning the surface of the DUT 1 20 μm square, 20 points × 20 points, that is, 400 points of light quantity As a result of focusing evaluation using value information, the upper limit of the resolution in the height direction was about 0.5 μm. At this time, the difference absolute value summation method described in the first embodiment was used for focusing evaluation.

(Embodiment 4)
In the fourth embodiment of the present invention, it is possible to partially increase or decrease the height resolution as in the above-described third embodiment even by using a light amount sensor in which the focal position is linearly changed. Is. As shown in FIG. 16, by providing the optical element 34 of the optical system, the focal position is optically distorted instead of linear. Thereby, the in-focus positions of the height Ha to the height Hi are arranged at intervals not equal to each other.

(Embodiment 5)
In the fifth embodiment of the present invention, the two-dimensional light quantity sensor 2s as shown in the second embodiment is used, similarly to the case where the one-dimensional light quantity sensor 2 (see FIG. 6) described in the first embodiment is used. Even when (see FIG. 8) is used, the height resolution can be partially increased or decreased by means using the optical element 34 of FIG. Of course, this method can be used in combination with a method in which the sensor elements are arranged at an inclination.

  The higher the sensitivity of the light quantity sensor and the faster the response speed, the faster the surface of the DUT 1 can be scanned. In order to realize the configuration described in the third embodiment, it is desirable that the sensor light receiving surface has a curved surface. From such a viewpoint, an element having a photomultiplier function such as a photomultiplier tube, a microchannel plate, or an image intensifier may be used as the light amount sensor. This is because these elements generally generate less noise even when the sensitivity is higher than that of an image sensor using a semiconductor such as a CCD or MOS, and are easier to arrange on a curved surface as well as on a flat surface.

  The shape measuring apparatus according to the present invention continuously obtains information without being stationary with respect to the object to be measured, and obtains image information with different focal planes without mechanical driving. It can be used in fields that require inspection of fine three-dimensional shapes, and measures the three-dimensional shape of the surface without stopping the object to be measured, such as during the continuous conveyance of sheet-like objects. It is also useful for applications that need to be done.

FIG. 3 is a block diagram showing the overall configuration of the shape measuring apparatus in the first embodiment. The figure explaining the operation | movement of the measurement of Embodiment 1. The figure which shows the concrete example of the maximum minimum method by the output value obtained from the light quantity sensor, the average difference sum of squares method (dispersion method), the average difference absolute value sum method, the difference absolute value summation method, and the difference square summation method Explanatory drawing of the configuration and principle of the shape measuring apparatus of the first embodiment The figure which shows the sensor element arranged in the one-dimensional direction of Embodiment 1. (A) A perspective view for explaining the shape measurement operation of the first embodiment, (b) a side view for explaining the shape measurement operation of the first embodiment, and (c) for explaining the shape measurement operation of the first embodiment. Showing the surface of the object to be measured (A) The figure which shows the light quantity value recorded by the light quantity sensor of Embodiment 1, (b) The figure which shows the light quantity value recorded by the light quantity sensor of Embodiment 1, (c) The light quantity sensor of Embodiment 1 Showing the light intensity value recorded by (A) The perspective view explaining the shape measurement operation in Embodiment 2, (b) The figure which shows the surface of the to-be-measured object explaining the shape measurement operation in Embodiment 2 The figure which shows the light quantity value recorded in time series by the light quantity sensor of Embodiment 2. FIG. The figure which shows the light quantity value which the light quantity sensor of Embodiment 2 rearranged The figure which shows the value for every height of the light quantity sensor of Embodiment 2. The figure which shows the result of having calculated the focus evaluation for every area | region with respect to the information of the light quantity sensor of Embodiment 2. The figure which shows the information of the shape obtained from the light quantity sensor of Embodiment 2. The figure which shows the method of raising the height resolution of the light quantity sensor in Embodiment 3. The figure which shows another method which raises the height resolution of the light quantity sensor of Embodiment 3. The figure which shows the method of changing the height resolution of a light quantity sensor with the optical element in Embodiment 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Measured object 2 Light quantity sensor 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2i Sensor element 2f-1, 2f-2, 2f-3 Sensor element 3 Optical system 4 Drive system 5 Control part 11a Point A
11b Point B
12 Measurement line 13 Surface 13b Black 13w White 14 Pattern 21a Point A '
21b Point B '
31 Light source 32 Lens 33 Mirror 34 Optical element

Claims (8)

An optical system for forming an image of the surface of the object to be measured having a black area and a white area in the same plane ;
A plurality of light quantity sensors arranged on focal planes corresponding to different surfaces of the object to be measured,
A drive system for scanning the surface of the object to be measured with the optical system;
Focusing is detected by performing an in-focus evaluation by processing electrical signals respectively corresponding to the black region and the white region obtained from the plurality of light quantity sensors, and the surface of the object to be measured is detected from the in-focus point. A signal processing unit for measuring the shape,
The shape measuring apparatus according to claim 1 , wherein the white region is arranged in front of or behind the black region with respect to a direction in which the measurement object is scanned in a plane having the same height .   The shape measuring apparatus according to claim 1, wherein the focal point is detected based on a magnitude of a sum of absolute values of signal differences obtained from the light quantity sensor. The shape measuring apparatus according to claim 1, wherein the object to be measured is separately applied to the black area and the white area .   4. The shape measuring apparatus according to claim 3, wherein a direction in which the plurality of light quantity sensors are arranged coincides with a direction in which the object to be measured is scanned. The object to be measured, to any one of claims 1-4, characterized in that it is formed of only a horizontal plane perpendicular to the direction perpendicular to the plane and the vertical plane for scanning the該被measured The shape measuring apparatus described. The shape measuring apparatus according to claim 1, wherein the planes having the same height are formed only from a black region and a white region . Before SL plurality of light amount sensors, the shape measuring apparatus according to any one of claims 1-6, characterized in that for imaging the region of the respective vertically downward.   The shape measuring apparatus according to claim 1, wherein the light quantity sensor uses an element having a photomultiplier function.

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